Diamonds, Hello "over here" !! as you probably know from the M/L site I'm a current owner of the 303/300 and was a previous owner of the Musical Fidelity 3.5. I feel both the A-5 and 303/300 are superb, I for one can't say the build quality is any better one over the other (both are assembled in China !) I like the balanced flexibility of the Cary along with it's tube rolling capabilities as well. The 303/300 does an excellent job of resolving the last bit of detail out of ones redbook CD collection.
I will say that I lucked out to a great deal on the "Gon" when I purchased mine last summer. For when one compares the MSRP of the two pieces ($2500 Musical fidelity A-5 vs. $4000 Cary 303/300) the Musical Fidelity almost looks like a bargain !!